The CSEM Response Researching Of Submarine Gas Hydrate

With economic globalization, the consumption of oil, coal and other traditionalenergy sources is growing, the situation of energy shortage is becoming seriously, ithas become a major issue to find a great new alternative energy in the world. In recentyears, countries around the world have invested a lot of manpower and materialresources to research new alternative energy. We found that there is a wealth ofnatural gas hydrate under the ocean floor, it can be used as a new and green energy inthe future. Therefore, accelerating the marine gas hydrate exploration, developmentand utilization has a great significance to alleviate the energy depletion crisis ofhuman society in the future.Marine seismic exploration is one of the most commonly used methods fordetecting gas hydrate, it can determine the presence of marine gas hydrates accordingto BSR on seismic profiles (bottom simulating reflector). However, BRS does notfully indicate the presence of gas hydrates. The study found that not all places of existBSR contain gas hydrates, where the presence of gas hydrates is not necessarilycontain BSR. Moreover, seismic method is not sensitive to hydrate saturation. Gashydrate reservoir is high resistance body comparing with the surrounding rock, itsconductivity is much smaller than the sea bottom sediment, Marine CSEM candetermine the presence of gas hydrate according to the difference between hydratereservoirs and surrounding rock, and improve the success rate of drilling. As a newgeophysical method rise in recent years, marine CSEM will quickly become one ofthe important means to survey marine gas hydrate.This paper introduces the basic principles of marine CSEM, and it designsone-dimensional model according to geological data, and analyses CSEM responsebased on the amplitude ratio, and studies marine gas hydrate effective abnormity,analyses CSEM response based on effective abnormity, studies the CSEM response ofthe hydrate reservoir thickness and resistivity variations in the reservoir, besides, it also demonstrates the effectiveness of transmitting and receiving system towed inhydrate exploration. It designs different1-D models to prove the applicability of themarine CSEM detects submarine gas hydrates in different regions according togeological data. This paper designs the2-D model based on the actual geological data,then it study the effects of frequencies and seafloor topography of the CSEM responseresults and the CSEM response characteristics of two adjacent gas hydrate reservoirmodels. Furthermore, it also studies the lateral resolution of the marine CSEM, anddiscusses the marine CSEM method for single hydrate reservoir and two adjacent gashydrate reservoirs lateral resolution capability.Studies have shown that the abnormity of the electric field vertical component ofmarine CSEM is bigger than the horizontal component, and marine CSEM is verysensitive to the hydrate reservoir thickness and resistivity variations, and the marineCSEM method has good lateral resolution for marine gas hydrate. According to theresult of1-D and2-D gas hydrate models, it demonstrates the feasibility of detectinggas hydrate with marine CSEM method, so it can provide some technical guidance formarine gas hydrate exploration in the future.